Standard window assemblies with double sash runs are made with sashes that cannot be removed from the sash runs without disassembling the window. However, so-called tilt-takeout window assemblies that permit sash removal are also in widespread use.
Generally, both the window sashes and jamb liners forming the sash runs are designed much differently for use with either standard or tilt-takeout window assemblies. Since both types of assemblies are widely used, window manufacturers are required to stock inventories of the different sashes and jamb liners. Of the two, the sashes are much more costly to stock in inventory than the jamb liners.
Accordingly, a number of attempts have been made to make both standard and tilt-takeout sashes compatible with one or the other window assembly types. For example, U.S. Pat. No. 3,724,131 to Schnormeier discloses special jamb liners for adapting standard window sashes to tilt-takeout window assemblies. However, Schnormeier's attempt requires costly slots be formed along jambs to receive the special liners.
Other jamb liners have been designed to adapt tilt-takeout sashes to standard window assemblies. These other liners have also not been very successful because they have not provided appropriate tracking for the tilt-takeout sashes. The liners are not well reinforced, and pairs of springs built into the liners for urging the liners against the sashes tend to warp the liners away from jambs along portions of sash runs not currently occupied by the sashes. Ordinarily, only one or the other of the springs is compressed by one of the sashes along most of the jamb liner length. The other spring is free to urge an adjacent portion of the liner away from the jamb.